Year Number 1989 35.92951 1994 35.39933 1995 37.15844 1996 34.54363 1997 35.74105 1999 34.10003 2000 32.22277 2001 36.29178 2002 37.88573 2003 32.15364 2004 34.20748 2005 33.54568 2006 32.99598 2007 32.91156 2009 32.33045 2010 32.47438 2011 31.98235 2012 29.7734 2013 35.77055 2014 36.61245 2015 27.45229 2016 27.13412